I had a similar truck, same engine, 4 spd. except it was longbed and not stepside. I have replaced rusted out sections of brake lines on nearly every truck I've owned, something to check for safety, and not hard to fix with a double flare took kit and sections of line from the auto parts store. They are great trucks, I would never have parted with mine had I not needed a Supercab to haul the family.
$1,000 - $1,500 would probably be fair.